The present invention is directed to a universal differential line driver integrated circuit and more specifically a line driver circuit which is programmable.
Line driver circuits are well-known in the art. A typical circuit is produced under type no. 9614 by, for example, both the Fairchild Corporation and the Advanced Micro Devices Corporation with the descriptive term differential line drivers. Such circuits have an active pull down and active pull up circuit which are split and brought out to adjacent pins. They drive either differential, single-ended, back matched or terminated transmission lines. Another type of line driver under the type no. 2614 has an active pull up output for high speed and good capacitance drive and is ideal for single ended transmission line driving.
National Semiconductor Corporation under model DM 7830 also manufactures a circuit similar to the type 2614.
Yet another type of driver is illustrated in U.S. Pat. No. 3,602,733 entitled "Three Output Level Logic Circuit" in the name of Edward M. Aoki and assigned to the present assignee. This patent discloses and claims a tri-state or three level logic circuit which has a high output impedance logic level as well as sourcing and sinking levels.
From the foregoing it is apparent that the circuit user depending upon his specific application must choose one of the foregoing types. In some cases the 9614 type can be modified to be single ended but this change is, for example, accomplished by soldering and thus is permanent.